WO2020211547A1 - Digital microfluidic substrate and digital microfluidic chip - Google Patents

Abstract

A digital microfluidic substrate and a digital microfluidic chip comprising same. The digital microfluidic substrate comprises: a first substrate (21); a driving transistor (22) disposed on the first substrate (21); a metal layer comprising a source (224) and a drain (225) of the driving transistor (22) and a first driving electrode (23) electrically connected to one of the source (224) and the drain (225); an insulating layer (24) covering the driving transistor (22) and the first driving electrode (23); a second driving electrode (27) electrically connected to the first driving electrode (23) by means of a via hole penetrating the insulating layer (24); and a first ground electrode (25) disposed in the insulating layer (24) and located between the metal layer and the second driving electrode (27).

Description

Digital microfluidic substrate and digital microfluidic chip

Cross references to related applications

This application claims the priority of Chinese Patent Application No. 201920534876.2 filed to the China Intellectual Property Office on April 18, 2019, the disclosure of which is incorporated herein by reference.

Technical field

The present disclosure relates to the technical field of microfluidics, and in particular to a digital microfluidic substrate and a digital microfluidic chip.

Background technique

Microfluidic technology can integrate basic operation units such as sample preparation, reaction, separation, and detection in biological, chemical, and medical analysis processes on a micron-scale chip, automatically completing the entire analysis process, because it can reduce costs and short detection time , High sensitivity and other advantages, has shown great prospects in biology, chemistry, medicine and other fields.

Summary of the invention

In one aspect, the present disclosure provides a digital microfluidic substrate, including:

First substrate

A driving transistor, which is arranged on the first substrate;

A metal layer, the metal layer including a source electrode and a drain electrode of the driving transistor and a first driving electrode electrically connected to one of the source electrode and the drain electrode;

An insulating layer covering the driving transistor and the first driving electrode;

A second driving electrode, the second driving electrode is electrically connected to the first driving electrode through a via hole penetrating the insulating layer;

The first ground electrode is disposed in the insulating layer and between the metal layer and the second driving electrode.

In an embodiment, the second driving electrode is configured to drive the movement of liquid droplets on the digital microfluidic substrate according to the state of the driving transistor.

In an embodiment, the insulating layer includes a first insulating layer covering the driving transistor and the first driving electrode, and a second insulating layer covering the first ground electrode and the first insulating layer.

In an embodiment, the orthographic projection of the first ground electrode on the first substrate covers the orthographic projection of the active layer of the driving transistor on the first substrate, and the material of the first ground electrode It is a non-transparent metal material.

In an embodiment, the driving transistor includes a plurality of driving transistors arranged in an array,

The digital microfluidic substrate further includes a plurality of gate signal lines extending in a row direction and a plurality of source signal lines extending in a column direction;

The sources of the plurality of driving transistors are respectively connected to the plurality of source signal lines, and the gates of the plurality of driving transistors are respectively connected to the plurality of gate signal lines; and

The orthographic projection of the first ground electrode on the first substrate covers the orthographic projection of the gate signal line and the source signal line on the first substrate.

In an embodiment, the orthographic projection of the first ground electrode on the first substrate covers the first area of the first substrate, and the first area is the first area of the first substrate except for the via hole. The area outside the area covered by the orthographic projection on the first substrate.

In an embodiment, the driving transistor includes a gate provided on the first substrate, a third insulating layer covering the gate, an active layer provided on the third insulating layer, and the drain The electrode is arranged on the active layer, the first driving electrode is arranged on the third insulating layer, and the drain and the first driving electrode are integrally formed.

In an embodiment, the sum of the projected area of the drain of the drive transistor and the first drive electrode on the first substrate is smaller than the projected area of the second drive electrode on the first substrate.

In an embodiment, the thickness of the first ground electrode is 10 nm-1000 nm.

In an embodiment, the digital microfluidic substrate further includes a first dielectric layer covering the second driving electrode and a first hydrophobic layer disposed on a side of the first dielectric layer away from the first substrate.

On the other hand, the present disclosure provides a digital microfluidic chip, including the above-mentioned digital microfluidic substrate and a counter substrate disposed opposite to the digital microfluidic substrate, and the counter substrate includes a second substrate And the second ground electrode, the second dielectric layer and the second hydrophobic layer which are sequentially arranged on the side of the second substrate facing the microfluidic chip, and the droplets are arranged between the first hydrophobic layer and the second hydrophobic layer between.

Description of the drawings

In order to explain the technical solutions of the embodiments of the present disclosure more clearly, the following will briefly introduce the drawings that need to be used in the description of the embodiments of the present disclosure. Obviously, the drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor.

Figure 1 shows a schematic structural diagram of a traditional digital microfluidic substrate;

Figure 2 shows a schematic structural diagram of a digital microfluidic substrate according to an embodiment of the present disclosure;

Figure 3 shows a plan view of a digital microfluidic substrate according to an embodiment of the present disclosure;

FIG. 4 shows a cross-sectional view taken along a line parallel to the extending direction of the source signal line in FIG. 3 in an embodiment of the present disclosure;

FIG. 5 shows a cross-sectional view taken along a line parallel to the extending direction of the gate signal line in FIG. 3 in an embodiment of the present disclosure;

Fig. 6 shows a schematic structural diagram of a digital microfluidic chip according to an embodiment of the present disclosure.

detailed description

The technical solutions in the embodiments of the present disclosure will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present disclosure.

As shown in Figure 1, the digital microfluidic substrate includes a first substrate 111, a gate 112, a first insulating layer 113, an active layer 114, a source 115, a drain 116, a second insulating layer 117, a driving electrode 118, The dielectric layer 119 and the hydrophobic layer 120, the driving electrode 118 is connected to the drain 116 through a via hole penetrating the second insulating layer 117, and the driving voltage is applied to the driving electrode 118 to drive the droplets.

However, because the digital microfluidic substrate requires a high driving voltage, generally tens of volts or even hundreds of volts, and the storage capacitance in the current digital microfluidic substrate is small, resulting in a faster leakage rate of the driving voltage, which affects The driving effect of the droplet.

2, there is shown a schematic structural diagram of a digital microfluidic substrate according to an embodiment of the present disclosure.

The embodiment of the present disclosure provides a digital microfluidic substrate, including: a first substrate 21, a driving transistor 22 and a first driving electrode 23 provided on the first substrate 21, and covering the driving transistor 22 and the first driving electrode 23 The first insulating layer 24; on the first insulating layer 24 is provided with a first ground electrode 25, the digital microfluidic substrate also includes a second insulating layer 26 covering the first ground electrode 25 and the first insulating layer 24, and set The second driving electrode 27 on the second insulating layer 26 is connected to the first driving electrode 23 through a via hole penetrating the second insulating layer 26 and the first insulating layer 24, and the first driving electrode 23 is connected to the driving The drain 225 of the transistor 22 is connected.

Alternatively, the first driving electrode 23 may be connected to the source electrode 224 of the driving transistor 22.

In an embodiment, the driving transistor 22 includes a gate electrode 221 disposed on the first substrate 21, a third insulating layer 222 covering the gate electrode 221, an active layer 223 disposed on the third insulating layer 222, and a third insulating layer 223 partially covering the third insulating layer. The insulating layer 222 and the metal layer of the active layer 223, the metal layer includes the source electrode 224, the drain electrode 225 and the first driving electrode 23, and the drain electrode 225 and the first driving electrode 23 are integrally formed.

When the drain electrode 225 of the driving transistor 22 is fabricated, the driving electrode 23 can be fabricated at the same time, so that the drain electrode 225 and the first driving electrode 23 are integrally formed, which makes the fabrication process of the digital microfluidic substrate easier. For example, the portion of the drain electrode 225 located on the third insulating layer 222 may be used as the first driving electrode. Alternatively, the drain 225 and the first driving electrode 23 may not be an integrally formed structure. The drain 225 and the first driving electrode 23 are manufactured in two separate steps, but the drain of the manufactured first driving electrode 23 and the driving transistor 22 is ensured. Pole 225 connection.

By applying a gate voltage to the gate 221 of the driving transistor 22, the driving transistor 22 is turned on, and then a driving voltage is applied to the source 224 of the driving transistor 22, so that the drain 225 of the driving transistor 22 is applied with a driving voltage. The drain 225 of the driving transistor 22 is connected to the first driving electrode 23, and the second driving electrode 27 is connected to the first driving electrode 23 through a via hole penetrating the second insulating layer 26 and the first insulating layer 24, so that the second driving electrode 27 is also applied with a driving voltage. Therefore, the driving of the droplets can be realized based on the driving voltage on the second driving electrode 27.

In the digital microfluidic substrate in the embodiment of the present disclosure, the first ground electrode 25 is arranged between the first driving electrode 23 and the second driving electrode 27, so that the first driving electrode 23 and the first ground electrode 25 and the second A plate capacitor is formed between the driving electrode 27 and the first ground electrode 25, which greatly increases the storage capacitor of the digital microfluidic substrate, thereby reducing the leakage speed of the driving voltage, so that the driving voltage can be kept relatively stable, thereby increasing The driving effect of the droplet.

It can be understood that the first ground electrode 25 is electrically insulated from both the first driving electrode 23 and the second driving electrode 27.

In a preferred embodiment of the present disclosure, the sum of the projection area of the drain 225 of the driving transistor 22 and the first driving electrode 23 on the first substrate 21 is slightly smaller than the projection of the second driving electrode 27 on the first substrate 21 area. That is to say, with respect to the source electrode 224, the area of the first driving electrode 23, the drain electrode 225, and the second driving electrode 27 is as large as possible.

By making the sum of the projected area of the drain 225 of the drive transistor 22 and the first drive electrode 23 on the first substrate 21 slightly smaller than the projected area of the second drive electrode 27 on the first substrate 21, and the first ground electrode 25 is located Between the first driving electrode 23 and the second driving electrode 27, the storage capacity of the two plate capacitors formed is stronger.

As shown in FIG. 2, the digital microfluidic substrate further includes a first dielectric layer 28 covering the second driving electrode 27 and a first hydrophobic layer 29 disposed on the first dielectric layer 28.

In the embodiment of the present disclosure, the first substrate 21 may be a glass substrate; the material of the gate 221 of the driving transistor 22 is any one of molybdenum, aluminum and copper, and the thickness of the gate 221 of the driving transistor 22 is 10nm-1000nm The material of the third insulating layer 222 is silicon nitride or silicon oxide, the thickness of the third insulating layer 222 is 10nm-2000nm; the material of the active layer 223 of the driving transistor 22 is amorphous silicon; the source 224 of the driving transistor 22 The material of the driving transistor 22 is any one of molybdenum, aluminum, and copper. The thickness of the source electrode 224 of the driving transistor 22 is 10nm-1000nm; the material of the drain electrode 225 of the driving transistor 22 is any one of molybdenum, aluminum and copper. The thickness of the drain 225 of the transistor 22 is 10 nm-1000 nm; the material of the first driving electrode 23 is any one of molybdenum, aluminum and copper, and the thickness of the first driving electrode 23 is 10 nm-1000 nm; the thickness of the first insulating layer 24 The material is silicon nitride or silicon oxide. The thickness of the first insulating layer 24 is 10nm-2000nm; the thickness of the first ground electrode 25 is 10nm-1000nm; the material of the second insulating layer 26 is silicon nitride or silicon oxide. The thickness of the insulating layer 26 is 10 nm-2000 nm; the material of the second driving electrode 27 is molybdenum, aluminum, copper, or ITO (Indium Tin Oxide), etc., and the thickness of the second driving electrode 27 is 10 nm-1000 nm; The material of the dielectric layer 28 is silicon nitride, silicon oxide, aluminum oxide or SU-8 photoresist, etc., the thickness of the first dielectric layer 28 is 10nm-10000nm; the material of the first hydrophobic layer 29 is polytetrafluoroethylene or containing Fluoropolymer or the like, the thickness of the first hydrophobic layer 29 is 10 nm-1000 nm.

In the actual manufacturing process, first the gate electrode 221 is formed on the first substrate 21 through a patterning process, and then a third insulating layer 222 covering the gate electrode 221 and the first substrate 21 is formed, and then the patterning process is performed on the third insulating layer 222. The active layer 223 is formed, and a metal layer is formed by a patterning process. The metal layer includes the first driving electrode 23 and partially covering the third insulating layer 222 and the active layer 223, so as to form the driving transistor 22 and the second substrate on the first substrate 21. A driving electrode 23, and the first driving electrode 23 is connected to the drain 225 of the driving transistor 22, and then a first insulating layer 24 covering the driving transistor 22 and the first driving electrode 23 is formed, and the first insulating layer 24 is patterned The first ground electrode 25 is formed by a process, and then a second insulating layer 26 covering the first ground electrode 25 and the first insulating layer 24 is formed, and a via hole penetrating the second insulating layer 26 and the first insulating layer 24 is formed by a patterning process, Then, the second driving electrode 27 is formed on the second insulating layer 26, so that the second driving electrode 27 is connected to the first driving electrode 23 through the via hole penetrating the second insulating layer 26 and the first insulating layer 24, and then forming a cover The first dielectric layer 28 of the two driving electrodes 27, and finally, a first hydrophobic layer 29 is formed on the first dielectric layer 28 to obtain a digital microfluidic substrate; wherein the patterning process includes photoresist coating, exposure, development, and etching. Processes such as etching and photoresist stripping.

It should be noted that the first driving electrode 23 is located on the side of the third insulating layer 222 of the driving transistor 22 away from the first substrate 21. The drain 225 and the first driving electrode 23 shown in FIG. The area on the active layer 223 is regarded as the area where the drain 225 is located, and the rest are areas where the first driving electrode 23 is located.

In another embodiment of the present disclosure, the orthographic projection of the first ground electrode 25 on the first substrate 21 covers the orthographic projection of the active layer 223 of the driving transistor 22 on the first substrate 21, and the orthographic projection of the first ground electrode 25 The material is non-transparent metal material.

In the embodiment, the orthographic projection of the first ground electrode 25 on the first substrate 21 covers the orthographic projection of the driving transistor 22 on the first substrate 21 and the orthographic projection of a part of the first driving electrode 23 on the first substrate.

In the traditional digital microfluidic substrate, the external light will irradiate the active layer of the driving transistor through the counter substrate arranged opposite to the digital microfluidic substrate, which will cause the leakage current of the driving transistor to increase and make the driving electrode The driving voltage is reduced, which affects the driving effect of the droplets; and the digital microfluidic substrate in the embodiment of the present disclosure adds a layer of the first ground electrode 25 made of non-transparent metal, and the first ground electrode 25 is in the first The orthographic projection on the substrate 21 covers the orthographic projection of the active layer 223 of the driving transistor 22 on the first substrate 21. When the external light passes through the counter substrate disposed opposite to the digital microfluidic substrate, it irradiates the digital microfluidic substrate At this time, the first ground electrode 25 can block the light above the active layer 223, so that external light will not irradiate the active layer 223 of the driving transistor 22, thereby reducing the leakage current of the driving transistor 22, so that the driving voltage can be kept grounded. It is more stable, thereby improving the driving effect of the droplets.

In an embodiment, the material of the first ground electrode 25 is a non-transparent metal material, which may be any one of molybdenum, aluminum, and copper.

3, there is shown a plan view of a digital microfluidic substrate according to an embodiment of the present disclosure, and FIG. 4 shows a cross-sectional view taken along a line parallel to the extension direction of the source signal line in the embodiment of the present disclosure, 5 shows a cross-sectional view taken along a line parallel to the extending direction of the gate signal line in the embodiment of the present disclosure.

In an embodiment of the present disclosure, the digital microfluidic substrate further includes a gate signal line 226 and a source signal line 227, and the orthographic projection of the first ground electrode 25 on the first substrate 21 covers the gate signal line 226 and the source signal line. An orthographic projection of the signal line 227 on the first substrate 21; the gate 221 of the driving transistor 22 is connected to the gate signal line 226, and the source 224 of the driving transistor 22 is connected to the source signal line 227.

In an embodiment, the digital microfluidic substrate includes a plurality of gate signal lines 226 extending in the row direction and a plurality of source signal lines 227 extending in the column direction. The gate signal lines 226 and the source signal lines 227 can be connected to each other. The digital microfluidic substrate is divided into a plurality of areas arranged in an array, each area is provided with a driving transistor 22, the gate 221 of the driving transistor 22 is connected to the gate signal line 226, and the source 224 of the driving transistor 22 is connected to the source The gate signal line 227 is connected, and a gate voltage signal is input to the gate signal line 226, so that the gate voltage is applied to the gate 221 of the driving transistor 22 connected to the gate signal line 226, so that the gate The driving transistors 22 connected to the signal line 226 are all turned on. By inputting a driving voltage signal to the source signal line 227, the driving voltage is applied to the source 224 of the driving transistor 22 connected to the source signal line 227. The drain 225 is connected to the first driving electrode 23, and the second driving electrode 27 is connected to the first driving electrode 23 through a via hole penetrating the second insulating layer 26 and the first insulating layer 24, so that the second driving electrode 27 is applied The upper driving voltage is based on the second driving electrode 27 to drive the droplets; in the embodiment, the second driving electrodes 27 in each area are independent of each other, based on the driving transistor 22 and the second driving electrode 27 in each area, and then The direction of movement of the droplets can be controlled. Therefore, it is possible that the second driving electrode 27 can drive the droplet based on the state of the driving transistor 22.

By setting the orthographic projection of the first ground electrode 25 on the first substrate 21 to cover the orthographic projection of the gate signal line 226 and the source signal line 227 on the first substrate 21, the first ground electrode 25 can shield the gate signal The line 226 and the source signal line 227 prevent the fringe electric field between the second driving electrode 27 and the gate signal line 226 and the source signal line 227 from affecting the movement of the droplet, thereby improving the stability and sensitivity of the droplet movement, so that Digital microfluidic substrate control is more precise.

It should be noted that the first ground electrodes 25 in each area are connected to each other, but they are not connected at the via holes connecting the second driving electrodes 27 and the first driving electrodes 23, so as to ensure that the first ground electrodes 25 are on the first substrate 21. The orthographic projection on the upper surface may cover the orthographic projection of the gate signal line 226 and the source signal line 227 on the first substrate 21.

In the embodiment, the gate signal line 226 is also provided on the first substrate 21, and is provided on the same layer as the gate electrode 221 of the driving transistor 22, and the material of the gate signal line 226 is the same as that of the gate electrode 221; The line 227 is disposed on the third insulating layer 222 and is disposed in the same layer as the source electrode 224 of the driving transistor 22, and the material of the source signal line 227 is the same as that of the source electrode 224.

In the embodiment of the present disclosure, by providing the driving transistor and the first driving electrode on the first substrate, and the first insulating layer covering the driving transistor and the first driving electrode, the first ground electrode, A second insulating layer covering the first ground electrode and the first insulating layer, and a second driving electrode disposed on the second insulating layer. The second driving electrode passes through the second insulating layer and the first insulating layer through the via hole and the first insulating layer. A driving electrode is connected, and the first driving electrode is connected to the drain of the driving transistor. By arranging the first ground electrode between the first driving electrode and the second driving electrode, a plate capacitor is formed between the first driving electrode and the first ground electrode and between the second driving electrode and the first ground electrode. The storage capacitor of the digital microfluidic substrate is increased, thereby reducing the leakage speed of the driving voltage, so that the driving voltage can be kept relatively stable, thereby improving the driving effect of the droplets.

Referring to Fig. 6, there is shown a schematic structural diagram of a digital microfluidic chip according to an embodiment of the present disclosure.

The embodiment of the present disclosure also provides a digital microfluidic chip, which includes the above-mentioned digital microfluidic substrate and a counter substrate 30 disposed opposite to the digital microfluidic substrate. The counter substrate 30 includes a second substrate 31 and is sequentially disposed The second ground electrode 32, the second dielectric layer 33 and the second hydrophobic layer 34 on the second substrate 31, and the droplet 40 is arranged between the first hydrophobic layer 29 and the second hydrophobic layer 34.

In an embodiment, the second substrate 31 may be a glass substrate; the material of the second ground electrode 32 is molybdenum, aluminum, copper, ITO, etc., the thickness of the second ground electrode 32 is 10 nm-1000 nm; the material of the second dielectric layer 33 It is silicon nitride, silicon oxide, aluminum oxide, or SU-8 photoresist, etc., the thickness of the second dielectric layer 33 is 10nm-10000nm; the material of the second hydrophobic layer 34 is polytetrafluoroethylene or fluoropolymer, etc., The thickness of the second hydrophobic layer 34 is 10 nm-1000 nm.

In the actual manufacturing process, the second ground electrode 32 is first formed on the second substrate 31, and then the second dielectric layer 33 is formed on the second ground electrode 32, and then a second hydrophobic layer is formed on the second dielectric layer 33 34. Obtain the counter substrate 30. Finally, the digital microfluidic substrate and the counter substrate 30 are boxed to obtain a digital microfluidic chip.

By applying a driving voltage to the second driving electrode 27 and applying a ground voltage to the second ground electrode 32, an electric field is formed between the second driving electrode 27 and the second ground electrode 32, and the movement of the droplet 40 is controlled by the formed electric field .

It should be noted that a accommodating cavity is formed between the digital microfluidic substrate and the counter substrate 30, and droplets 40 can be subsequently injected into the accommodating cavity based on the second driving electrode 27 and the counter substrate on the digital microfluidic substrate. To the second ground electrode 32 on the substrate 30, the droplet 40 is controlled to move in the digital microfluidic chip.

In addition, for the specific description of the digital microfluidic chip, reference may be made to the description of the foregoing embodiment, which will not be described here.

In the embodiment of the present disclosure, by providing the driving transistor and the first driving electrode on the first substrate, and the first insulating layer covering the driving transistor and the first driving electrode, the first ground electrode, A second insulating layer covering the first ground electrode and the first insulating layer, and a second driving electrode disposed on the second insulating layer. The second driving electrode passes through the second insulating layer and the first insulating layer through the via hole and the first insulating layer. A driving electrode is connected, and the first driving electrode is connected to the drain of the driving transistor. By arranging the first ground electrode between the first driving electrode and the second driving electrode, a plate capacitor is formed between the first driving electrode and the first ground electrode and between the second driving electrode and the first ground electrode. The storage capacitor of the digital microfluidic substrate is increased, thereby reducing the leakage speed of the driving voltage, so that the driving voltage can be kept relatively stable, thereby improving the driving effect of the droplets.

Although the preferred embodiments of the embodiments of the present disclosure have been described, those skilled in the art can make additional changes and modifications to these embodiments once they learn the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present disclosure.

Finally, it should be noted that in this article, the terms "include", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements is not only Including those elements, but also including other elements not explicitly listed, or also including the inherent elements of the process, method, article or terminal equipment. If there are no more restrictions, the element defined by the sentence "including a..." does not exclude the existence of other same elements in the process, method, article or terminal device that includes the element.

The above are only specific implementations of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present disclosure. It should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims (11)

A digital microfluidic substrate, including: First substrate A driving transistor, which is arranged on the first substrate; A metal layer, the metal layer including a source electrode and a drain electrode of the driving transistor and a first driving electrode electrically connected to one of the source electrode and the drain electrode; An insulating layer covering the driving transistor and the first driving electrode; A second driving electrode, the second driving electrode is electrically connected to the first driving electrode through a via hole penetrating the insulating layer; and The first ground electrode is disposed in the insulating layer and between the metal layer and the second driving electrode. The digital microfluidic substrate according to claim 1, wherein the second driving electrode is configured to drive the movement of liquid droplets on the digital microfluidic substrate according to the state of the driving transistor. The digital microfluidic substrate according to claim 1, wherein: The insulating layer includes a first insulating layer covering the driving transistor and the first driving electrode, and a second insulating layer covering the first ground electrode and the first insulating layer. The digital microfluidic substrate according to claim 1, wherein the orthographic projection of the first ground electrode on the first substrate covers the orthographic projection of the active layer of the driving transistor on the first substrate And the material of the first ground electrode is a non-transparent metal material. The digital microfluidic substrate according to claim 1, wherein: The driving transistor includes a plurality of driving transistors arranged in an array, The digital microfluidic substrate further includes a plurality of gate signal lines extending in a row direction and a plurality of source signal lines extending in a column direction; The sources of the plurality of driving transistors are respectively connected to the plurality of source signal lines, and the gates of the plurality of driving transistors are respectively connected to the plurality of gate signal lines; and The orthographic projection of the first ground electrode on the first substrate covers the orthographic projection of the gate signal line and the source signal line on the first substrate. The digital microfluidic substrate according to claim 5, wherein the orthographic projection of the first ground electrode on the first substrate covers a first area of the first substrate, and the first area is the The area of the first substrate excluding the area covered by the orthographic projection of the via on the first substrate. The digital microfluidic substrate according to claim 3, wherein the driving transistor comprises a gate provided on the first substrate, a third insulating layer covering the gate, and a third insulating layer provided on the third insulating layer. The active layer on the layer, the drain is arranged on the active layer, the first driving electrode is arranged on the third insulating layer, the drain and the first driving electrode are integrally formed structure. The digital microfluidic substrate according to claim 1, wherein the sum of the projected area of the drain of the driving transistor and the first driving electrode on the first substrate is smaller than that of the second driving electrode on the first substrate. A projection area on the substrate. The digital microfluidic substrate according to claim 1, wherein the thickness of the first ground electrode is 10 nm-1000 nm. The digital microfluidic substrate according to claim 1, wherein the digital microfluidic substrate further comprises a first dielectric layer covering the second drive electrode and a first dielectric layer disposed on the first dielectric layer away from the A first hydrophobic layer on one side of the substrate. A digital microfluidic chip, comprising the digital microfluidic substrate as claimed in any one of claims 1-8 and a counter substrate arranged opposite to the digital microfluidic substrate, the counter substrate comprising a second A substrate and a second ground electrode, a second dielectric layer, and a second hydrophobic layer that are sequentially arranged on the side of the second substrate facing the microfluidic chip, and droplets are arranged on the first hydrophobic layer and the second hydrophobic layer between.

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